Step A - Base Damage
Look up the axe's base damage in the static reference table; the Twig Splitter sits at the bottom, the Mythic end-game axe at the top.
Step B - Player Scaling
Scale by player level: each level adds about 3% multiplicative damage beyond level 1 [INFERRED-FROM-COMMUNITY].
Step C - DPS Math
Convert damage-per-swing to DPS using the axe's swing interval. Oak Hatchet swings faster than the Twig Splitter; the end-game axe closes in on 0.65 s per swing.
Step D - Cash Multiplier
Multiply DPS by the sell multiplier, biome multiplier, and rebirth multiplier to derive cash per hour.
Step E - Composite Score
Combine DPS, cash per hour, rarity score, and upgrade payback on the 0-100 composite scale. S tiers land at 85-100, C tiers at 0-49.
Step F - Payback Hours
Read the payback hours. If the next axe does not pay for itself in your current shift, defer the purchase and bank the cash.